Copyright Joey Paquet, 2000 1
Introduction to UML:The Unified Modeling Language
Copyright Joey Paquet, 2000 2
What is the UML?• UML stands for Unified Modeling Language• The UML combines the best of the best from
– Data modeling concepts (entity relationship diagrams)– Business modeling (work flow diagrams)– Object modeling– Component modeling
• The UML is a language standard for visualizing,specifying, constructing, and documenting the artifacts of asoftware-intensive system
• It can be used with all processes, throughout thedevelopment life cycle, and across differentimplementation technologies
Copyright Joey Paquet, 2000 3
UML Concepts• The UML may be used to:
– Display the boundary of a system & its major functions using usecases and actors
– Illustrate use case realizations with interaction diagrams
– Represent a static structure of a system using class diagrams
– Model the behavior of objects with state transition diagrams
– Reveal the physical implementation architecture with component& deployment diagrams
Copyright Joey Paquet, 2000 4
Putting the UML to Work• A University wants to computerize its registration system
– The Registrar sets up the curriculum for a semester• One course may have multiple course offerings
– Students select 4 primary courses and 2 alternate courses
– Once a student registers for a semester, the billing system isnotified so the student may be billed for the semester
– Students may use the system to add/drop courses for a period oftime after registration
– Professors use the system to receive their course offering rosters
– Users of the registration system are assigned passwords which areused at logon validation
Copyright Joey Paquet, 2000 5
Actors• An actor is someone or something that must interact with
the system under development
Student
Registrar
Professor
Billing System
Copyright Joey Paquet, 2000 6
Use Cases• A use case is a pattern of behavior the system exhibits
– Each use case is a sequence of related transactions performed byan actor and the system in a dialogue towards achieving a set ofrelated services
• Actors are examined to determine their needs– Registrar -- maintain the curriculum
– Professor -- request roster
– Student -- maintain schedule
– Billing System -- receive billing information from registration
Maintain ScheduleMaintain Curriculum Request Course Roster
Copyright Joey Paquet, 2000 7
Documenting Use Cases• A flow of events document is created for each use case
– Written from an actor point of view
• Details what the system must provide to the actor when theuse case is used
• Typical contents– How the use case starts and ends
– Normal flow of events
– Alternate or exceptional flows of events
Copyright Joey Paquet, 2000 8
Flow of Events• Maintain Curriculum
– This use case begins when the Registrar logs onto the Registration Systemand enters his/her password. The system verifies that the password isvalid (E-1) and prompts the Registrar to select the current semester or afuture semester (E-2). The Registrar enters the desired semester. Thesystem prompts the professor to select the desired activity: ADD,DELETE, REVIEW, or QUIT.
– If the activity selected is ADD, the S-1: Add a Course subflow isperformed.
– If the activity selected is DELETE, the S-2: Delete a Course subflow isperformed.
– If the activity selected is REVIEW, the S-3: Review Curriculum subflowis performed.
– If the activity selected is QUIT, the use case ends.– ...
Copyright Joey Paquet, 2000 9
Use Case Diagram• Use case diagrams are created to visualize the relationships
between actors and use cases
Student
Registrar
Professor
Maintain Schedule
Maintain Curriculum
Request Course Roster
Billing System
Copyright Joey Paquet, 2000 10
Use Case Relationships• As the use cases are documented, other use case
relationships may be discovered– A <<uses>> relationship shows behavior that is common to one or
more use cases
– An <<extends>> relationship shows optional behavior
Register for courses
<<uses>>
Logon validation<<uses>>
Maintain curriculum
Copyright Joey Paquet, 2000 11
Use Case Realizations• The use case diagram presents an outside view of the
system
• Interaction diagrams describe how use cases are realized asinteractions among societies of objects
• Two types of interaction diagrams– Sequence diagrams
– Collaboration diagrams
Copyright Joey Paquet, 2000 12
Sequence Diagram• A sequence diagram displays object interactions arranged
in a time sequence
: Student registration form
registration manager
math 101
1: fill in info
2: submit
3: add course(joe, math 101)
4: are you open?5: are you open?
6: add (joe)7: add (joe)
math 101 section 1
Copyright Joey Paquet, 2000 13
Collaboration Diagram• A collaboration diagram displays object interactions
organized around objects and their links to one another
: Registrar
course form : CourseForm
theManager : CurriculumManager
aCourse : Course
1: set course info2: process
3: add course
4: new course
Copyright Joey Paquet, 2000 14
Class Diagrams• A class diagram shows the existence of classes and their
relationships in the logical view of a system
• UML modeling elements in class diagrams– Classes and their structure and behavior
– Association, aggregation, dependency, and inheritancerelationships
– Multiplicity and navigation indicators
– Role names
Copyright Joey Paquet, 2000 15
Classes• A class is a collection of objects with common structure,
common behavior, common relationships and commonsemantics
• Classes are found by examining the objects in sequenceand collaboration diagram
• A class is drawn as a rectangle with three compartments
• Classes should be named using the vocabulary of thedomain– Naming standards should be created
– e.g., all classes are singular nouns starting with a capital letter
Copyright Joey Paquet, 2000 16
Classes
RegistrationForm
RegistrationManager
Course
Student
CourseOfferingProfessor
ScheduleAlgorithm
Copyright Joey Paquet, 2000 17
Operations• The behavior of a class is represented by its operations
• Operations may be found by examining interactiondiagrams
registration form
registration manager
3: add course(joe, math 01)
RegistrationManager
addCourse(Student,Course)
Copyright Joey Paquet, 2000 18
Attributes• The structure of a class is represented by its attributes
• Attributes may be found by examining class definitions,the problem requirements, and by applying domainknowledge
Each course offeringhas a number, location and time
CourseOffering
numberlocationtime
Copyright Joey Paquet, 2000 19
Classes
RegistrationForm
RegistrationManager
addStudent(Course, StudentInfo)Course
namenumberCredits
open()addStudent(StudentInfo)
Studentnamemajor
CourseOfferinglocation
open()addStudent(StudentInfo)
ProfessornametenureStatus
ScheduleAlgorithm
Copyright Joey Paquet, 2000 20
Relationships• Relationships provide a pathway for communication
between objects
• Sequence and/or collaboration diagrams are examined todetermine what links between objects need to exist toaccomplish the behavior -- if two objects need tocommunicate there must be a link between them
• Three types of relationships are:– Association
– Aggregation
– Dependency
Copyright Joey Paquet, 2000 21
Relationships• An association is a bidirectional connection between
classes– An association is shown as a line connecting the related classes
• An aggregation is a stronger form of relationship wherethe relationship is between a whole and its parts– An aggregation is shown as a line connecting the related classes
with a diamond next to the class representing the whole
• A dependency relationship is a weaker form ofrelationship between a client and a supplier where theclient does not have semantic knowledge of the supplier– A dependency is shown as a dashed line pointing from the client to
the supplier
Copyright Joey Paquet, 2000 22
Finding Relationships• Relationships are discovered by examining interaction
diagrams– If two objects must “talk” there must be a pathway for
communication
Registration Manager
Math 101: Course
3: add student(joe)
RegistrationManager
Course
Copyright Joey Paquet, 2000 23
Relationships
RegistrationForm
RegistrationManager
Course
Student
CourseOfferingProfessor
addStudent(Course, StudentInfo)
namenumberCredits
open()addStudent(StudentInfo)name
major
location
open()addStudent(StudentInfo)
nametenureStatus
ScheduleAlgorithm
Copyright Joey Paquet, 2000 24
Multiplicity and Navigation• Multiplicity defines how many objects participate in a
relationship– Multiplicity is the number of instances of one class related to ONE
instance of the other class
– For each association and aggregation, there are two multiplicitydecisions to make: one for each end of the relationship
• Although associations and aggregations are bidirectionalby default, it is often desirable to restrict navigation to onedirection
• If navigation is restricted, an arrowhead is added toindicate the direction of the navigation
Copyright Joey Paquet, 2000 25
Multiplicity and Navigation
RegistrationForm
RegistrationManager
Course
Student
CourseOfferingProfessor
addStudent(Course, StudentInfo)
namenumberCredits
open()addStudent(StudentInfo)
major
location
open()addStudent(StudentInfo)
tenureStatus
ScheduleAlgorithm
10..*
0..*
1
1
1..*4
3..10
0..41
Copyright Joey Paquet, 2000 26
Inheritance• Inheritance is a relationship between a superclass and its
subclasses
• There are two ways to find inheritance:– Generalization
– Specialization
• Common attributes, operations, and/or relationships areshown at the highest applicable level in the hierarchy
Copyright Joey Paquet, 2000 27
Inheritance
RegistrationForm
RegistrationManager
Course
Student
CourseOfferingProfessor
addStudent(Course, StudentInfo)
namenumberCredits
open()addStudent(StudentInfo)
major
location
open()addStudent(StudentInfo)
tenureStatus
ScheduleAlgorithm
name
RegistrationUser
Copyright Joey Paquet, 2000 28
The State of an Object• A state transition diagram shows
– The life history of a given class
– The events that cause a transition from one state to another
– The actions that result from a state change
• State transition diagrams are created for objects withsignificant dynamic behavior
Copyright Joey Paquet, 2000 29
State Transition Diagram
InitializationOpen
entry: Register studentexit: Increment count
Closed
Canceled
do: Initialize course
do: Finalize course
do: Notify registered students
Add Student / Set count = 0
Add student[ count < 10 ]
[ count = 10 ]
Cancel
Cancel
Cancel
Copyright Joey Paquet, 2000 30
The Physical World• Component diagrams illustrate the organizations and
dependencies among software components
• A component may be– A source code component
– A run time component or
– An executable component
Copyright Joey Paquet, 2000 31
Component Diagram
Course CourseOffering
Student Professor
Course.dll
People.dll
Course
User
Register.exeBilling.exe
BillingSystem
Copyright Joey Paquet, 2000 32
Deploying the System• The deployment diagram shows the configuration of run-
time processing elements and the software processes livingon them
• The deployment diagram visualizes the distribution ofcomponents across the enterprise.
Copyright Joey Paquet, 2000 33
Deployment Diagram
Registration Database
Library
Dorm
Main Building
Copyright Joey Paquet, 2000 34
Part III
The Iterative Approach to
Software Design
Copyright Joey Paquet, 2000 35
The Iterative Approach• Continuous integration
– Not done in one lump near the delivery date
• Frequent, executable releases– Some internal; some delivered
• Attack risks through demonstrable progress– Progress measured in products, not documentation or engineering
estimates
Copyright Joey Paquet, 2000 36
Resulting Benefits• Releases are a forcing function that drives the development
team to closure at regular intervals– Cannot have the “90% done with 90% remaining” phenomenon
• Can incorporate problems/issues/changes into futureiterations rather than disrupting ongoing production
• The project’s supporting elements (testers, writers,toolsmiths, etc.) can better schedule their work
Copyright Joey Paquet, 2000 37
Managing Risk Phase-by-Phase• Inception
– Gather information about the project
– Bracket the project’s risks
• Elaboration– Develop a common understanding of the system’s scope and
desired behavior by exploring scenarios with end users and domainexperts
– Establish the system’s architecture
– Design common mechanisms to address system-wide issues
Copyright Joey Paquet, 2000 38
Managing Risk Phase-by-Phase• Construction
– Refine the architecture
– Risk-driven iterations
– Continuous integration
• Transition– Facilitate user acceptance
– Measure user satisfaction
• Post-deployment cycles– Continue evolutionary approach
– Preserve architectural integrity
Copyright Joey Paquet, 2000 39
Risk Reduction Drives Iterations
Initial Project RisksInitial Project Scope
Revise Overall Project Plan• Cost• Schedule• Scope/Content
Plan Iteration N• Cost• Schedule
Assess Iteration N
Risks EliminatedRevise Project Risks• Reprioritize
Develop Iteration N• Collect cost andquality metrics
Define scenarios toaddress highest risks
Iteration N
Copyright Joey Paquet, 2000 40
Use Cases Drivethe Iteration Process
Inception Elaboration Construction Transition
Iteration 1 Iteration 2 Iteration 3
Iteration PlanningRqmts Capture
Analysis & DesignImplementation
Test Prepare Release
“Mini-Waterfall” Process
Copyright Joey Paquet, 2000 41
The Iteration Life Cycle:A Mini-Waterfall Model
• Results of previous iterations• Up-to-date risk assessment• Controlled libraries of models,
code, and tests
Release descriptionUpdated risk assessmentControlled libraries
Iteration Planning
Requirements Capture
Analysis & Design
Implementation
Test
Prepare Release
Selected scenarios
Copyright Joey Paquet, 2000 42
Iteration Life Cycle Activities• Iteration planning
– Before the iteration begins, the general objectives of the iterationshould be established based on
• Results of previous iterations (if any)
• Up-to-date risk assessment for the project
– Determine the evaluation criteria for this iteration
– Prepare detailed iteration plan for inclusion in the developmentplan
• Include intermediate milestones to monitor progress
• Include walkthroughs and reviews
Copyright Joey Paquet, 2000 43
Iteration Life Cycle Activities• Requirements Capture
– Select/define the use cases to be implemented in this iteration
– Update the object model to reflect additional domain classes andassociations discovered
– Develop a test plan for the iteration
Copyright Joey Paquet, 2000 44
Iteration Life Cycle Activities• Analysis & Design
– Determine the classes to be developed or updated in this iteration
– Update the object model to reflect additional design classes andassociations discovered
– Update the architecture document if needed
– Begin development of test procedures
• Implementation– Automatically generate code from the design model
– Manually generate code for operations
– Complete test procedures
– Conduct unit and integration tests
Copyright Joey Paquet, 2000 45
Iteration Life Cycle Activities• Test
– Integrate and test the developed code with the rest of the system(previous releases)
– Capture and review test results
– Evaluate test results relative to the evaluation criteria
– Conduct an iteration assessment
• Prepare the release description– Synchronize code and design models
– Place products of the iteration in controlled libraries
Copyright Joey Paquet, 2000 46
Work Allocation in each Iteration• Work to be accomplished in an iteration is determined by
– The (new) use cases to be implemented
– The rework to be done
• Packages are convenient for developers– High-level packages can be assigned to teams
– Lower-level packages can be assigned to individual developers
• Use Cases make convenient work packages for test andassessment teams
Copyright Joey Paquet, 2000 47
Iteration Assessment• Assess iteration results relative to the evaluation criteria
established during iteration planning:– Functionality
– Performance
– Quality measures
• Consider external changes that have occurred during thisiteration– For example, changes to requirements, user needs, etc.
• Determine what rework, if any, is required and assign it tothe remaining iterations
Copyright Joey Paquet, 2000 48
Selecting Iterations• How many iterations do I need?
– On projects taking 18 months or less, 3 to 6 iterations are typical
• Are all iterations on a project the same length?– Iteration length may vary by phase. For example, elaboration
iterations may be shorter than construction iterations
Copyright Joey Paquet, 2000 49
The First Iteration• The first iteration is usually the hardest
– Requires the entire development environment and most of thedevelopment team to be in place
– Many tool integration issues, team-building issues, staffing issues,etc. must be resolved
• Teams new to an iterative approach are usually overly-optimistic
• Be modest regarding the amount of functionality that canbe achieved in the first iteration– Otherwise, completion of the first iteration will be delayed,
– The total number of iterations reduced, and
– The benefits of an iterative approach reduced
Copyright Joey Paquet, 2000 50
Remember That• The main reason for using the iterative life cycle:
– You do not have all the information you need up front
– Things will change during the development period
• You must expect that– Some risks will not be eliminated as planned
– You will discover new risks along the way
– Some rework will be required; some lines of code developed for aniteration will be thrown away
– Requirements will change along the way
Top Related